1. Field of the Invention
The present invention relates to an image inspecting device, an image forming system, and a computer program product.
2. Description of the Related Art
Printed matter has been manually inspected in the related art. Alternatively, in recent years, devices for making an inspection as postprocessing of offset printing have been used. Such devices generate a master image as a reference by manually selecting a non-defective image from among read images of the printed matter to be electronically read, compares a portion of the master image with a corresponding portion of the read image of the printed matter to be inspected, and determines a defect of the printed matter based on a difference degree therebetween.
On the other hand, plateless printing devices such as of electrophotography that have been widely used in recent years are suitable for printing a small number of copies. There are many cases in which printing content varies from page to page such as variable data printing. Accordingly, it is inefficient for plateless printing devices to generate the master image from the printed matter to be compared unlike offset printers. To address this problem, it is considered to generate the master image from print data. In this manner, the variable data printing can be efficiently performed.
In inspection processing on such an image, whether the printed matter has a defect is determined by setting a certain threshold of the difference degree described above. The difference degree is a result obtained by aligning positions and equalizing sizes of the read image and the master image generated from the print data, and comparing both images with each other for each pixel.
To cause a determination result of the defect to be closer to a result intended by a user, a certain threshold described above needs to be set as intended by the user. As a technique related to a change of the threshold by the user, for example, developed is a technique of recalculating and displaying the number of images, when the threshold is changed, in a quality class corresponding to the changed threshold (for example, refer to Japanese Patent Application Laid-open No. 2005-205797).
By utilizing the technique disclosed in Japanese Patent Application Laid-open No. 2005-205797, when the threshold is changed, a change in the number of images included in each quality class can be checked. However, a change in the difference degree of the image that is determined as a defect cannot be checked, so that the threshold intended by the user can hardly be set.
In view of such a situation, there is a need to provide an image inspecting device, an image forming system, and a computer program product that can easily change the threshold used for inspecting the image to a value intended by the user.